(Sorry, but if it stands the test of time, that's likely what it will be called . . .)
Did a One-Two Punch Form the Solar System? May 24, 2007 by J. Kelly Beatty It's an exciting time to be a cosmochemist. State-of-the-art laboratory techniques for analyzing traces of elemental isotopes are now so good that the "born on" date for billion-year-old rocks and minerals can be pinpointed to well within a million years. This kind of precision has opened dramatic new windows on how our solar system came to exist 4,567,200,000 years ago. Take, for example, the radioisotope iron-60 (60Fe). The discovery that ancient meteorites contained this key geochemical marker, together with aluminum-26 and calcium-41, requires that some violent astrophysical event led to the collapse of the interstellar cloud that formed our solar system. And since 60Fe can only be forged during a supernova, for decades theorists have generally agreed that shock waves from the demise of a nearby star triggered the cloud's collapse. But most likely it didn't happen that way. In the May 25th issue of Science, Martin Bizzarro (University of Copenhagen) and five colleagues describe their studies of 60Fe in some of the oldest known meteorites. Iron-60 has a half-life of just 1.5 million years, so Bizzarro and his team assayed the nickel-60 created when the short-lived isotope decayed. Surprisingly, they found that the very oldest meteorites contain vestiges of 26Al but lacked the decayed 60Fe that should have been there. Yet the iron was present in meteorites that crystallized about a million years later. By implication, the solar system was already coming together when the putative supernova went "bang!" Full article at <http://skytonight.com/news/One-Two_Punch.html>. -- Ronn! :) _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
